Motion Planning Of Continuum Robot For Aircraft Fuel Tank Inspection

The manual inspection for aircraft fuel tank gets such drawbacks like high labor intensity, high risks and low efficiency. So an automatic robot for aided inspection, which can bring the sensors to the target zone, is in urgent need. A continuum robot for aircraft fuel tank inspection was designed to improve the performance of manual maintenance. The main part of the robot is the continuous cable-driven multi-joints. With a high degree of freedom, the arm can bend and rotate flexibly, and bring the camera to the target zone. Path planning is necessary for the aircraft fuel tank robot to move from the tank entry to the target zone while avoiding obstacles successfully.Path planning for these devices is challenging due to the multi variables and strong nonlinearity of the complex kinematics models, meanwhile, the irregular distribution of pipelines in the fuel tank exacerbates the difficulty. In terms of the complicated tank space and the characteristic structure of continuum robot, a constrained nonlinear optimization formulation was presented to describe the path planning problem.Firstly, PATH for continuum arm was well defined. With the definition, the following work could be carried on.Secondly, a fast search method based on Region Clipping was presented to decrease the computing time complexity. On the basis of kinematics models of aircraft fuel tank robot, the continuity of functions based on forward kinematics was analyzed. And based on the analysis, a region clipping search method was presented to calculate the configuration of the Snake Arm. Compared with the blind search, the novel method got a much lower computing time complexity, and could yield the robot configuration quickly. Simulations were designed to demonstrate the effectiveness and speediness of Region Clipping.Thirdly, path planning without obstacles based on dimension reduction was designed. The search for the rotation angle was removed by transforming the three dimensional space planning to the two dimensional plane problem. Arbitrary point in the fuel tank could be reached was achieved through Matlab simulations, and results demonstrated the feasibility of path planning.Finally, the collision-free path planning based on projection strategy was adopted. Considering the distribution characteristics if the pipes in the tank, projection strategy was presented to simplify the constraint conditions. The obstacles were regarded as projections on the bottom plane through dividing the space zone. Experiments using Matlab programing were reasonably designed, and the effectiveness and speediness was verified.